HUP0103729A2 - Flexible membranes - Google Patents

Abstract

The subject of the invention is an elastomer insulating membrane, as well as a cushioning structural element and footwear containing it. The elastomeric insulating membrane according to the invention contains a microlayered polymer composite with an average thickness of at least 50 mm, where the microlayered polymer composite contains at least ten microlayers, each with a maximum thickness of about 100 mm, which microlayers are alternately formed from at least one fluid insulating material and at least one elastomeric material. The essence of the cushioning structural element is that it contains an elastomer insulating membrane according to the invention. The essence of the footwear is that it contains at least one hose under pressure, which is made of the membrane according to the invention. HE

Description

! ' p 0003 72 9 * PUBLICATION FORM

Elastomeric insulating membrane and cushioning containing it

STRUCTURAL ELEMENT AND FOOTWEAR

The invention relates to an elastomeric insulating membrane, as well as to a cushioning structural element and footwear comprising the same.

The membranes of the invention are particularly useful for making pressurized hoses, such as cushioning structures. The membranes of the invention are elastic and have an extremely low gas permeation rate for nitrogen and other gases used for inflating hoses and cushioning structures.

Thermoplastic and thermosetting plastics are widely used in membranes due to their insulating properties against fluids (i.e., gases or liquids). Such fluid-insulating films are used, for example, in plastic packaging films and other packaging materials. Another common application of plastics with good fluid-insulating properties is the manufacture of inflatable hoses.

Inflatable tubes are used as cushioning structural elements in a variety of products, such as vehicle tires, balls, heavy equipment storage tanks, and footwear, especially shoes. It is often desirable to use thermoplastics because thermoplastics can be recycled and reprocessed into new products, thereby reducing waste during manufacturing processes and facilitating the recycling of the article at the end of its useful life. Although thermoplastic insulating films can be bent to a certain extent depending on their thickness, these same thermoplastic insulating films are generally not sufficiently elastic for many applications. Elastic materials, or elastomers, are capable of essentially completely recovering their original shape and size after the deforming force is removed, even if the part formed from them has undergone significant deformation. Elastomeric properties are important in many applications, including inflatable hoses for footwear and pressure tanks.

Footwear, especially shoes, usually consists of two main components: the upper and the sole. The overall purpose of the upper is to provide a secure and comfortable fit.

94171-8452/SZT/SZT

hold the foot. Ideally, the upper should be made of a material or combination of materials that are attractive, durable and comfortable. The sole, made of durable material, is designed to be flexible and protect the foot during use. The sole also provides increased cushioning and shock absorption during sports activities, thus protecting the wearer's foot, ankle and legs from significant forces. The impact force during running can be two or three times the wearer's body weight, while other sports activities, such as basketball, can involve forces of six to ten times the wearer's body weight. Many shoes today - especially sports shoes - contain some kind of flexible shock-absorbing material or structural element to cushion the foot and body during strenuous sports activities. These flexible, shock-absorbing materials or structural elements are commonly referred to in the footwear industry as midsoles. Such flexible, shock-absorbing materials or components may also be used in the insole of a shoe, which generally refers to the portion of the shoe upper located directly below the flat surface of the foot.

Gas-filled tubes can be incorporated into the midsole or sole of shoes. Gas-filled tubes are typically inflated to a significant pressure to provide protection against the forces acting on the foot during strenuous athletic activities. Such tubes typically fall into two broad categories: those that are permanently inflated, such as those disclosed in U.S. Patents Nos. US-4,183,156 and US-4,219,945 (Rudy), and those that utilize a pump and valve system, such as those disclosed in U.S. Patent No. US-4,722,131 (Huang).

The permanently inflated hoses described in US-4,183,156 are sold by Nike Inc. (Beaverton, Oregon, USA) under the brand name Airsole™. The permanently inflated hoses of this type of shoe are made using a thermoplastic material with elastomeric properties inflated with a gas with a high molecular weight, low solubility coefficient, known in the industry as supergas, and the supergas used is, for example, SF ₆ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , etc. Supergases are expensive, however, and it is desirable to achieve the permanently inflated state with less expensive gases, such as air or nitrogen. For example, US-4,340,626 (Rudy), Diffusion Pumping Apparatus Self-Inflating Device US patent hose forming,

-3.”· ·’ ·.*' **/ • · · · · ·· ··· selectively permeable foil sheets are inflated to a given pressure with a gas or gas mixture. The diffusion rate of the gas or gases used through the selectively permeable hose to the external environment is ideally relatively low, while the diffusion rate of gases in the atmosphere, such as nitrogen, oxygen or argon, is relatively high, so that they are able to penetrate the hose. This leads to an increase in the total pressure inside the hose, since the partial pressure of nitrogen, oxygen or argon from the air is added to the partial pressure of the gas or gases with which the hose was originally inflated. The principle of relative unidirectional addition as described above, used to increase the total pressure of gases in the hose, is known in the literature as a diffusion pump.

Prior to and shortly after the introduction of Air-Sole™ brand trainers, most of the earlier midsole tubes used in the footwear industry were made of a single layer of gas barrier type film made of polyvinylidene chloride based materials such as Sárank (registered trademark of Dow Chemical Co.). These materials are inherently rigid plastics, exhibit relatively rapid fatigue under bending stress, are poorly weldable, and have only a small amount of elongation. Films composed of two gas barrier materials have also been used, for example, U.S. Patent No. 5,122,322 (Momose) discloses a film in which a first thermoplastic resin carries continuous layers of a second thermoplastic resin extending parallel to the plane of the film. The first thermoplastic resin is selected from polyolefin, polystyrene, polyacrylonitrile, polyester, polycarbonate or polyvinyl chloride resins and modified resins. The second resin may be polyamide, saponified ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinylidene chloride or polyacrylonitrile copolymer. The film is formed by extruding the first resin with a first die and the second resin with a second die in such a way that the two extrudates are simultaneously fed into a static mixer where said layers are formed. One or two outer layers may also be laminated to the film. Although the films in question are taught to have an oxygen transmission rate of 0.12-900 cm ³ /m ² .day.atm at a temperature of 20°C - i.e. they are generally suitable for forming cushioning materials in packaging and transport materials - they are not flexible or pliable enough to form cushioning tubes used in footwear.

-4Additional laminated plastics consisting of two different types of insulating material are also known today. These laminated plastics are formed by a large number of relatively thin layers of different materials. A process for producing a multilayer film (consisting of at least about 10 layers) using at least two different thermoplastic plastic streams is described, for example, in US Patents Nos. 3,565,985, 4,937,134, 5,202,074, 5,094,788, 5,094,793, 5,380,479, 5,540,878 and 5,626,950 (all to Schrenk et al.), and in US Patent No. 3,557,265. (Chisolm et al.) and US5,269,995 (Ramathan et al.) are also US patents. The thermoplastic molten resin streams are combined into a layered stream and then passed through a layering device to produce the multilayer film. The layering processes described in the above patents are used to produce iridescent films. In order to achieve the rainbow effect, the thickness of the layers responsible for the iridescence can range from 0.05 pm to 5 pm. The various thermoplastic materials are selected so that the difference in refractive indices of the individual layers is maximized to achieve maximum iridescence in the multilayer film. Gas barrier materials do not form films that can absorb repeated impacts without deformation or fatigue failure, as is required for the membranes of inflatable tubes or cushioning structural elements.

In the case of hoses used in footwear, known composite or laminated plastic films can also be a source of a number of problems, such as, but not limited to, delamination, delamination, gas diffusion or capillary action through welded interfaces, low elongation leading to wrinkling of the inflated product, opaque appearance of the finished hoses, reduced puncture resistance and tensile strength, difficulty in forming by blowing and/or hot-gluing or RF welding, high cost, and difficulties in encapsulating the foam and reinforcing it with adhesive. In some previously known multilayer hoses, tie layers or adhesives have been used during the production of the laminated plastic to provide sufficiently high adhesion strength between the individual layers to avoid the above problems. However, such bonding layers and adhesives make it impossible to remove the waste generated during the production of the product.

-5regrinding and recycling of possible waste materials to create a usable product, thus making production more expensive and generating more waste during their application. The use of adhesive also increases the cost and complexity of the manufacturing process of laminated plastics. The disadvantages of this type of laminated plastics are discussed in more detail in, for example, US-4,340,626, US-4,936,029 and US-5,042,176.

Composite films can be formed from layers of materials with significantly different properties in addition to a combination of two gas barrier layers. Composites made from different materials are particularly advantageous in the case of hoses used in footwear, since there are many, often conflicting, requirements for the membranes used to manufacture such hoses. For example, as already mentioned, such a membrane must have excellent gas barrier properties with respect to both the inflation gas and the gases that make up the air, while also being elastic and resistant to fatigue cracking. The materials used in the manufacture of hoses used in footwear must also be resistant to the damaging effects of the fluids contained therein and the external environment acting on them. The problem of the diverse and sometimes contradictory requirements for the properties of these types of membranes and films usually arises when the laminated plastic consists of at least two layers of different materials, where one layer provides the long-lasting flexibility of an elastomer, while the other layer provides resistance to fluids.

According to one possible approach, at least two different materials are reacted or mixed together, thereby allowing each of the different materials to contribute in its own way to the properties of the graft copolymer or blend layer. The composition of such a graft copolymer is described, for example, in US-5,036,110 (Moureaux), which describes a flexible membrane formed from a film made of a graft copolymer of thermoplastic polyurethane and an ethylene-vinyl alcohol copolymer for a hydropneumatic collection tank. The ethylene-vinyl alcohol copolymer constitutes 5-20% of the graft copolymer. The ethylene-vinyl alcohol copolymer is dispersed in the polyurethane polymer and a certain degree of grafting occurs between the two polymers. The graft copolymer is an ethylene-vinyl alcohol copolymer

-6·::· <· ’··*· forms islands in the polyurethane matrix. The film in question forms an intermediate layer between the two thermoplastic polyurethane layers of the hydropneumatic ignition tank membrane. Although the nitrogen permeation rate is lower than that of unmodified polyurethane, the gas permeation rate of the film formed by the matrix containing gas-barrier resin particles is not as low as the gas permeation rate of the composite film containing a continuous layer of fluid-impermeable material.

Another possible approach is to consider laminated plastics. In this case, the use of a membrane consisting of a first layer of a thermoplastic elastomer, such as a thermoplastic polyurethane, and a second layer of an insulating material, such as a copolymer of ethylene and vinyl alcohol, eliminates the need for adhesive bonding layers, provided that hydrogen bonds are formed in the membrane segments between the first and second layers. Laminates of such flexible materials and fluid-impermeable materials are disclosed, for example, in US-5,713,141. U.S. Patent No. 08/299,287, Cushioning Device with Improved Flexible Barrier Membrane, filed on August 31, 1994; 08/684,351, Laminated Resilient Flexible Barrier Membranes, filed on July 19, 1996; 08/475,276, Barrier Membranes Including a Barrier Layer Employing Aliphatic Thermoplastic Polyurethanes, filed on June 7, 1995; 08/475,275, filed on June 7, 1995; Barrier Membranes Including a Barrier Layer Employing Polyester Polyols, and Membranes of Polyurethane Based Materials Including Polyester Polyols, filed December 12, 1995, and assigned U.S. Patent Application Serial No. 08/571,160. In addition, the membranes disclosed in the above applications enable the formation of flexible, gas-filled, permanently inflated cushioning structures for footwear that are believed to provide significant technical advantages.

-7 represent a development, the membranes of the present invention represent much more efficient membranes than the membranes discussed in the aforementioned applications.

It is therefore an object of the invention to develop membranes and membrane materials that exhibit increased flexibility and resistance to unwanted permeation of fluids, such as inflation gas. It is also an object of the invention to provide an elastic membrane for gas-inflatable hoses, such as nitrogen, with a gas permeation rate of up to about 10 ^cm3 / ^m2.day.atm.4

Our investigations have shown that inflatable hoses with improved elastomeric properties and low gas permeation rates can be produced from microlayered polymer composites. The microlayered polymer composites of the invention can be used to produce a membrane with durable/long-lasting elastomeric properties for use in a variety of applications, particularly in pressure hoses for use in footwear and collection tanks and other cushioning structural elements. By durable or long-lasting is meant that the membrane, preferably over a wide temperature range, exhibits excellent resistance to fatigue cracking, i.e. the membrane can be subjected to repeated bending and/or deformation and recovery without delamination along the layer interfaces or cracking through the entire thickness of the membrane. In the present application, the term membrane is preferably understood to mean a free-standing film separating two fluids (whether gases or liquids). Films laminated or painted onto other products with functions other than separating fluids are not included in this definition of membrane.

A microlayered polymer composite is constructed from microlayers of a first plastic, also known as a structural or elastomeric material, which provides flexibility and pliability, and a second plastic, also known as a fluid barrier material, which provides low gas permeation rates. For the same total amount of fluid barrier material, the microlayers of the non-elastomeric fluid barrier material result in a membrane that is much more elastomeric and has much greater flexibility than the currently widely used laminated plastics, which contain significantly thicker layers of barrier material.

Our goal has been achieved by providing an elastomeric insulating membrane comprising a microlayered polymer composite having an average thickness of at least about 50 pm, wherein the microlayered polymer composite comprises at least about ten microlayers each having a thickness of at most about 100 pm, said microlayers being alternately formed of at least one fluid insulating material and at least one elastomeric material.

Accordingly, the present invention provides a membrane for creating an inflatable hose, for example for footwear or pressure vessels, at least one layer of which is formed by the microlaminated polymer composite according to the invention. The microlaminated plastic composite according to the invention has rubber-like or elastomeric mechanical properties, which are provided by a structural material that repeatedly and reliably absorbs high forces occurring during use without damage or fatigue cracking. For applications such as footwear or pressure vessels, it is particularly important that the membrane according to the invention exhibits excellent durability under cyclic loading. The gas barrier material used in the microlaminated plastic composite provides a low gas transmission rate, which allows the hose to remain inflated and provide cushioning for substantially the nominal life of the footwear or pressure vessel without periodic re-inflation and pressurization.

The gas transmission rate of the membrane according to the invention may be up to 10 cm ³ /m ² .atm.day for nitrogen. The relative permeability, transmission and diffusion of various film materials are measured using the method described in the ASTMD-1434-82-V standard. According to the ASTMD-1434-82-V standard, the quantities in question are calculated using the following relationships:

- seepage:

(gas volume) / [(area) χ (time) χ (pressure difference)] = permeation (GTR) / (pressure difference) = cm ³ / (m ² ).(24 hours).(Pa)

- transfer:

[(gas volume) χ (film thickness)] / [(area) χ (time) χ (pressure difference)] = throughput [(GTR) χ (film thickness)] / (pressure difference) = [(cm ³ ).(m)] / [(m ² ).(24 hours).(Pa)]

-diffusion (at 101.325 kPa pressure):

(gas volume) / [(area) χ (time)] = gas transmission rate (GTR) = cm ³ / (m ² ).(24 hours)

Possible embodiments of the membrane according to the invention are described in more detail below with reference to the attached drawing, where the

- Figure 1 shows a side view of a sports shoe that is one of the applications of the membrane, with a part of the midsole removed to illustrate the cross-section;

- Figure 2 shows the sports shoe shown in Figure 1 in a side view, with a portion of the sole removed to illustrate another cross-sectional view;

- Figure 3 is a cross-section 3-3 of the sports shoe illustrated in Figure 1;

- Figure 4 is a perspective view of one possible exemplary embodiment of a tubular, two-layer cushioning structural element;

- Figure 5 is a section 4-4 of the cushioning structural element outlined in Figure 4;

- Figure 6 is a perspective view of one possible exemplary embodiment of a tubular, three-layer cushioning structural element;

- Figure 7 is a section 6-6 of the cushioning structural element outlined in Figure 6;

- Figure 8 is a perspective view of a cushioning structural element formed from the membrane according to the invention for use in shoes;

- Figure 9 is a side view of the cushioning structural element illustrated in Figure 8;

- Figure 10 shows a perspective view of a further cushioning structural element formed from the membrane according to the invention for use in a shoe; - Figure 11 shows a side view of a further cushioning structural element formed from the membrane according to the invention for use in a shoe in a position embedded in a shoe;

- Figure 12 is a perspective view of the cushioning structural element shown in Figure 11;

the

- Figure 13 is a top view of the cushioning structural element shown in Figure 11;

- Figure 14 shows a side view of a further cushioning structural element formed from the membrane according to the invention for use in shoes, in a position embedded in a shoe;

- Figure 15 is a perspective view of the cushioning structural element illustrated in Figure 14;

- Figure 16 is a top view of the cushioning structural element illustrated in Figure 14;

- Figure 17 is a perspective view of a further cushioning structural element formed from the membrane according to the invention for use in shoes;

- Figure 18 is a side view of the cushioning structural element shown in Figure 17;

- Figure 19 is a longitudinal section of a product formed from a laminated plastic membrane according to the invention;

- Figure 20 is a longitudinal section of a further product formed from a laminated plastic membrane according to the invention;

- Figure 21 is a side view of a sheet forming device;

- Figure 22 illustrates the distribution tube of the sheet coextrusion device illustrated in Figure 21 in cross section;

- Figure 23 is a side view of a tube forming device;

- Figure 24. Cross-section of a tubular, single-layer membrane;

- Figure 25 is a longitudinal section of a product formed from a single-layer membrane according to the invention; while

- Figure 26 is a photograph of a cross-section of the microlaminated plastic composite according to the invention.

The hoses according to the invention are made of an elastic membrane comprising at least one layer of the microlaminated plastic composite according to the invention, wherein the microlaminated plastic composite according to the invention comprises alternately at least one thin layer of fluid-insulating material and structural elastomeric material. However, it is also advantageous to use a microlaminated plastic composite comprising layers of different fluid-insulating materials and/or different elastomeric materials, wherein the different layers form a regular, repeating layer sequence. In addition to the layers of elastomeric material and fluid-insulating material, further layers may be used, arranged alternately with the layers of the regular, repeating layer sequence formed by these layers. The microlaminated plastic composite according to the invention comprises at least ten layers, preferably at least twenty layers, more preferably at least thirty layers, and even more preferably at least fifty layers. The microlaminated polymer composite may also comprise several thousand layers, as is known in the art.

- 11 It will be apparent to those skilled in the art that the number of layers will depend on factors such as the type of materials selected, the thickness of each layer, the total thickness of the microlaminated plastic composite, the processing conditions used to create the multilayer structure, and the end use of the composite. Microlaminated elastic membranes preferably consist of a number of layers ranging from about ten to about one thousand, more preferably from about thirty to about one thousand, and even more preferably from about fifty to about five hundred.

The average thickness of the individual layers of the fluid-insulating materials can range from a few nm to about 100 pm. The average thickness of the individual layers is preferably up to about 2.5 pm, and more preferably between about 0.01 pm and 2.5 pm. For example, the thickness of the individual layers of insulating material can be, on average, about 1.2 pm. By using thinner layers of fluid-insulating material, the extensibility of the membrane hose can be increased.

Suitable elastomeric materials for forming structural layers include, but are not limited to, polyurethane elastomers, including elastomers based on both aromatic and aliphatic isocyanates; flexible polyolefins, including flexible homopolymers and copolymers of polyethylene and polypropylene; styrene-based thermoplastic elastomers; polyamide elastomers, polyamide-ether elastomers; ester-ether or ester-ester elastomers; flexible ionomers; thermoplastic vulcanizates; flexible polyvinyl chloride homopolymers and copolymers; flexible acrylic polymers, and blends and mixtures thereof, such as polyvinyl chloride blends and polyvinyl chloride-polyurethane blends. The different elastomeric materials can be mixed with each other in the structural layers of the microlayered polymer composites, or they can be formed as separate layers of the microlayered polymer composite.

Particularly suitable are thermoplastic polyester polyurethanes, polyether polyurethanes and polycarbonate polyurethanes, including but not limited to polytetrahydrofurans, polyesters, polycaprolactone polyesters, ethylene oxide and propylene oxide polyethers, and polyurethanes polymerized using copolymers of ethylene oxide and propylene oxide as diol reagents. Said polymerized diol-based polyurethanes may be a polymer diol (e.g. polyester diol, polyether diol, polycaprolactone diol, polytetrahydrofuran diol or polycarbonate diol),

-12 — is prepared by the reaction of at least one polyisocyanate and, optionally, at least one chain extender compound. Chain extender compounds are herein understood to mean compounds having at least two functional groups that react with isocyanate groups. The diol-based polymerized polyurethane is preferably substantially linear (i.e., substantially all of the reactants are difunctional).

The polyester diols used in the preparation of the thermoplastic polyurethanes of the present invention are generally obtained by condensation polymerization of polyacid compounds and polyol compounds. The polyacid compounds and polyol compounds are preferably difunctional, i.e., dibasic acids and diacids are used in the preparation of substantially linear polyester diols, but small amounts of monofunctional, trifunctional, and higher functional materials (up to about 5 mol%) may also be used. Suitable dicarboxylic acids include, but are not limited to, glutaric acid, succinic acid, malonic acid, oxalic acid, phthalic acid, hexahydrophthalic acid, adipic acid, maleic acid, and mixtures thereof. Suitable polyols include, but are not limited to, those in which the chain extender is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, cyclohexanedimethanol, 2-ethyl-1,6-hexanediol, Esterdiol 204 (available from Eastman Chemical Co.), 1,4-butanediol, 1,5-pentanediol, 1,3-propanediol, butylene glycol, neopentyl glycol, and combinations thereof. In some cases, small amounts of triols or higher functionality polyols, such as trimethylolpropane or pentaerythritol, are also added. In a preferred embodiment of the membrane of the invention, adipic acid is used as the dicarboxylic acid and 1,4-butanediol is used as the diol. Typical catalysts for esterification polymerization include proton acids, Lewis acids, titanium alcoholates, and dialkyl tin oxides.

The polymer polyether or polycaprolactone diol reagent used in the preparation of thermoplastic polyurethanes advantageous from the point of view of the membrane of the invention reacts a diol initiator, e.g. ethylene or propylene glycol, with a lactone or alkylene oxide chain extender reagent. Chain extender reagents advantageous from the point of view of the reaction are, for example, ε-caprolactone, ethylene oxide and propylene oxide. Lactones that open to a ring under the influence of active hydrogen are well known in practice. Lactones suitable from the point of view of the solution of the invention include - the

-13-without requiring specificity - for example, ε-caprolactone, γ-caprolactone, β-butyrolactone, β-propyrolactone, γ-butyrolactone, α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-decanolactone, δ-decanolactone, γ-nonanelactone, γ-octane-lactone and combinations thereof. In a preferred embodiment of the membrane according to the invention, ε-caprolactone is used. Lactones preferred for the practical production of the membrane according to the invention can be characterized by the structural formula (A), where n is a positive integer between 1 and 7, and R represents one or more hydrogen atoms or a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms. The compounds previously mentioned for polyester synthesis also represent preferred catalysts. In another possible manufacturing process, the sodium salt formed with the hydroxyl group of molecules reacting with the lactone ring can also initiate the reaction.

In another possible manufacturing process, a diol initiator is reacted with an oxirane-containing compound to form a polyether diol for use in polyurethane polymerization. The oxirane-containing compound is preferably an alkylene oxide or a cyclic ether, particularly preferably a compound selected from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and combinations thereof. The alkylene oxide polymer segments may be formed by polymerization products of, but are not limited to, ethylene oxide, propylene oxide, 1,2-cyclohexene oxide, 1-butene oxide, 2-butene oxide, 1-hexene oxide, tert-butylethylene oxide, phenyl glycidyl ether, 1-decene oxide, isobutylene oxide, cyclopentene oxide, 1-pentene oxide, and combinations thereof. Alkylene oxide polymerization is typically base-catalyzed. The polymerization can be carried out, for example, starting from a catalytic amount of a hydroxyl-containing initiator and a soda such as potassium hydroxide, sodium methoxide or potassium tert-butoxide, and adding the alkylene oxide at a rate necessary to ensure that a sufficient amount of monomer is continuously present for the polymerization reaction. By simultaneous addition, random copolymerization of two or more alkylene oxide monomers can be achieved, while by sequential addition, block polymerization of them can be achieved. Homopolymers or copolymers of ethylene oxide or propylene oxide are preferred.

Tetrahydrofuran polymerizes under known conditions to form successively repeating -[CH2CH2CH2CH2O]- units. Tetrahydrofuran is cationic

-14 polymerizes by ring-opening reactions, such as in the presence of counterions such as SbF", AsF ₆ , PF ₆ , SbCl', BF, CF3SO3, FSO, and CIO; The reaction is initiated by the formation of a tertiary oxonium ion. The polytetrahydrofuran segment can be prepared as a living polymer and terminated by reaction with the hydroxyl group of any of the aforementioned diols.

Aliphatic polycarbonate diols are prepared by reacting diols with dialkyl carbonates (e.g. diethyl carbonate), diphenyl carbonate or dioxolanones (e.g. cyclic carbonates formed by five or six membered rings) as catalysts, for example alkali metals, tin catalysts or titanium compounds. Preferred diols include, but are not limited to, the diols already mentioned. Aromatic polycarbonates are usually prepared by reacting bisphenols, such as bisphenol A, with phosgene or diphenyl carbonate.

The polymer diols used in polyurethane synthesis, such as the polymer polyester diols described above, preferably have a weight average molecular weight (e.g., as determined by the ASTM D-4274 method) of from about 300 to about 4,000, more preferably from about 400 to about 3,000, and even more preferably from about 500 to about 2,000. The polymer diol generally forms the soft segment of the elastomeric polyurethane.

The elastomeric polyurethane may be synthesized by reacting one or more of the above polymer diols with one or more compounds containing at least two isocyanate groups and, optionally, a chain extender. The elastomeric polyurethanes are preferably linear, so that the polyisocyanate compound is preferably substantially difunctional. The diisocyanate compounds used for the production of thermoplastic polyurethanes used in the membranes of the invention include, but are not limited to, isophorone diisocyanate (IPDI), methylene bis-4-cyclohexyl isocyanate (H ₁₂ MDI), cyclohexyl diisocyanate (CHDI), m-tetramethyl xylene diisocyanate (mTMXDI), p-tetramethyl xylene diisocyanate (p-TMXDI), ethylene diisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, 1,6-diisocyanatohexane (hexamethylene diisocyanate or HDI), 1,4-butylene diisocyanate, lysine diisocyanate, 1,4-methylene bis(cyclohexyl isocyanate), various isomers of toluene diisocyanate, meta-xylylene diisocyanate and para-xylylene diisocyanate, 4-chloro-1,3-phenyl diisocyanate, 1,5tetrahydronaphthalene diisocyanate, 4,4'-dibenzyl diisocyanate and 1,2,4-benzene

-15triisocyanate, xylene diisocyanate (XDI) and combinations thereof. Diphenylmethane diisocyanate (MDI) is particularly preferred for the membrane of the invention.

The active hydrogen-containing chain extenders that can be used generally contain at least two active hydrogen groups, such as diols, dithiols, diamines, or compounds containing a mixture of hydroxyl, thiol, and amine groups, including, for example, alkanolamines, aminoalkyl mercaptans, and hydroxyalkyl mercaptans. The molecular weight of the chain extenders is preferably between about 60 and about 400. The use of alcohols and amines is preferred. Diols commonly used as polyurethane chain extenders include, but are not limited to, 1,6-hexanediol, cyclohexane dimethanol (sold as CHDM by Easterman Chemical Co.), 2-ethyl-1,6-hexanediol, Esterdiol 204 (sold by Easterman Chemical Co.), 1,4-butanediol, ethylene glycol and its smaller oligomers, such as diethylene glycol, triethylene glycol and tetraethylene glycol, propylene glycol and its smaller oligomers, such as dipropylene glycol, tripropylene glycol and tetrapropylene glycol, 1,3-propanediol, neopentyl glycol, dihydroxyalkylated aromatic compounds, such as hydroquinone and bis-(2-hydroxyethyl) ethers of resorcinol, p-xylene-cc,oc-diol, m-xylene-cx,ct -diol, bis-2-hydroxymethyl ether, and mixtures thereof. Suitable diamine chain extenders include, but are not limited to, p-phenylenediamine, m-phenylenediamine, benzidine, 4,4'-methylenedianiline, 4,4'-methylenebis-(2-chloroaniline), ethylenediamine, and combinations thereof. Other commonly used chain extenders include amino alcohols, such as ethanolamine, propanolamine, butanolamine, and combinations thereof. Preferred chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and combinations thereof.

In addition to the above-mentioned difunctional chain extenders, trifunctional chain extenders, such as trimethylolpropane, 1,2,6-hexanetriol and glycerol, and/or monofunctional active hydrogen-containing compounds, such as butanol or dimethylamine, may also be present in small amounts. The trifunctional chain extenders and/or monofunctional compounds used have active hydrogen-containing groups, as

and their content is not more than 5.0 equivalent % based on the total weight of the reaction product and the active hydrogen-containing groups used.

The reaction of the polyisocyanate, the polymer diol and the chain extender additive is typically initiated by heating the compounds, for example by a melt reaction in a twin screw extruder. Typical catalysts for this reaction include catalysts formed from organotin compounds, for example tin(II) octoate. The ratio of the polymer diol, for example polyester diol, to the chain extender can generally be varied over a relatively wide range, the specific value of the ratio being largely dependent on the desired hardness of the final polyurethane elastomer. For example, the ratio of polyester diol to chain extender can be between 1:0 and 1:12, preferably between 1:1 and 1:8. The ratio of diisocyanate(s) used is preferably such that the total ratio of equivalents of isocyanate to equivalents of active hydrogen-containing materials is between 0.95:1 and 1.10:1, and more preferably between 0.98:1 and 1.05:1. The weight ratio of polymer-diol segments in the polyurethane polymer typically ranges from about 35% to about 65%, preferably from about 35% to about 50% of the weight of the polyurethane polymer.

In certain applications, it may be desirable to use mixtures of polyurethanes in the formation of structural layers of a microlayered polymer composite. This is the case, for example, when the tendency to hydrolysis is of particular importance. For example, a polyurethane containing soft segments of polyetherdiols or polyesterdiols formed from the reaction mixture of a carboxylic acid and a diol, in which the repeating units of the reaction products contain at least eight carbon atoms, can be mixed with polyurethanes containing polyesterdiols having repeating units of up to eight carbon atoms or with reaction products of branched diols. Preferably, polyurethanes other than polyurethanes containing polyesterdiols having repeating units of up to eight carbon atoms or containing an oxygen atom attached to a tertiary carbon will be present in the mixtures in an amount of up to 30% by weight (i.e., for example, 70% by weight of a polyethylene glycol adipate-based polyurethane and 30% by weight of an isophthalate-based polyesterdiol-based polyurethane). Typical examples of polyester diols where the reaction product contains at least eight carbon atoms are poly(ethylene glycol isophthalate), poly(1,4-butanediol isophthalate), and poly(1,6-hexanediol isophthalate).

-17·”· .:λ <' ^: ·ί*

Instead of different thermoplastic polyurethane mixtures, a single polyurethane containing different soft segments can also be used. Also without claim to completeness, the soft segment can also contain, in addition to soft segments containing a total of up to eight carbon atoms, polyether diols, polyester diols containing at least eight carbon atoms, and mixtures thereof. It is to be noted here that the total amount of soft segment components present as a reaction product of a carboxylic acid and a diol containing at least eight carbon atoms can be at most 30% by weight of the total weight of the soft segments on the polyurethane. Thus, at least 70% by weight of the repeating units of the soft segment are a reaction product of a carboxylic acid and a diol, where the total number of carbon atoms in the reaction product is at most eight.

It should also be noted that polyurethanes that are advantageous for the membranes of the invention can be added in a number of ways to polyurethanes that are made from polyesters with repeating units containing at least eight carbon atoms up to 30% by weight. Polyurethanes made from polyester diols containing at least 30% by weight of repeating units containing at least eight carbon atoms can be added in the form of finished polymers to polyurethanes made from polyester diols containing at least 70% by weight of repeating units containing at least eight carbon atoms. According to another possible solution, a single polyurethane can be obtained from a mixture of polyester diols if the mixture contains at least 70% by weight of repeating units containing at least eight carbon atoms, while the remainder of the mixture is made up of repeating units containing at least eight carbon atoms as described above. Polyurethane can be prepared from a single diol obtained by the reaction of a dicarboxylic acid with a diol in which 70% by weight of the repeating units in the polyester diol are repeating units with up to eight carbon atoms. Combinations of the methods mentioned are also possible. Of the acids containing at least six carbon atoms, isophthalic acid and phthalic acid are preferably used.

Of the many thermoplastic polyurethanes that are advantageously used to form the outer layer 32 of Figures 5 and 7, either ester or ether based polyurethanes have proven to be particularly advantageous.

Examples of suitable materials in this respect include polyamide-ether elastomers sold under the PEBAX® brand by Elf Atochem, ester-ether elastomers sold under the HYTREL® brand by DuPont, and DSM

-18• · · · · ··♦ ··

Engineering's ester-ester and ester-ether elastomers marketed under the ARNITEL® brand, Advanced Elastomeric Systems' thermoplastic vulcanizates marketed under the SANTORENE® brand, Emser's elastomeric polyamides marketed under the GRILAMID® brand, Dow Chemical Company's (Midland, Ml, USA) elastomeric polyurethanes marketed under the PELLETHANE® brand, BASF Corporation's (Mt. Olive, NJ, USA) polyurethanes marketed under the ELLASTOLLAN® brand, BAYER's polyurethanes marketed under the TEXIN® and DESMOPAN® brands, Morton's polyurethanes marketed under the MORTHANE® brand, and B.F.Goodrich Co.'s polyurethanes marketed under the ESTANE® brand.

In addition to the elastomeric materials of the structural layers, the microlaminated polymer composite of the invention also comprises layers of fluid barrier material. Preferred fluid barrier materials include, but are not limited to, ethylene vinyl alcohol copolymers, polyvinyl chloride, polyvinylidene polymers and copolymers, especially polyvinylidene chloride, polyamides, including amorphous polyamides, acrylonitrile polymers, including acrylonitrile methyl acrylate copolymers, polyurethane engineering plastics, polymethylpentene resins, ethylene carbon monoxide copolymers, liquid crystal polymers, polyethylene terephthalate, polyetherimides, polyacrylimides, and other polymeric materials known to have low gas permeation rates. Mixtures and alloys of these materials, such as combinations of polyimides and crystalline polymers (e.g. liquid crystal polymers), polyamides and polyethylene terephthalate, and combinations of polyamides and styrenes, are also suitable. Ethylene-vinyl alcohol copolymers are particularly preferred, especially those in which the proportion of ethylene copolymer is between about 25 mol% and about 50 mol%, more preferably between about 25 mol% and about 40 mol%. Ethylene-vinyl alcohol copolymers are prepared by complete hydrolysis of ethylene-vinyl acetate copolymers. The various fluid barrier materials can be incorporated into the structural layers of the microlayered polymer composite in the form of mixtures or can be arranged as separate layers in the microlayered polymer composite.

Examples of special materials suitable for this purpose include acrylonitrile copolymers, such as those sold by BP Chemicals Inc. under the trade name BAREX°.

- 19 — ·::· <· ^: ·'· polyurethane engineering plastics, such as those sold by Dow Chemical Corp. under the ISOPLAST® trademark; ethylene-vinyl alcohol copolymers, such as those sold by EVAL Company of America (EVALCA, Lisle, Illinois, USA) under the EVAL® trademark, by Nippon Gosnei Co. Ltd. (New York, USA) under the SOARNOL® trademark, by Solvay under the CLARENE® trademark, and by DuPont under the SELAR® OH trademark; polyvinylidene chloride sold by Dow Chemical under the SARAN® trademark and by Solvay under the IXAN® trademark; liquid crystal polymers sold by Hoechst Celanese under the VECTRA® trademark and by Amoco Chemicals under the XYDAR® trademark; nylon sold by Mitsubishi Gas Chemical Co. Ltd, Solvay, and Toyoba under the MDX®6 trademark; NOVAMID®X21 sold by Mitsubishi, SELAR®PA sold by DuPont, and GELON A-100 amorphous nylons sold by General Electric Company; polyacrylimide copolymer sold by Rohm & Haas under the KAMAX® trademark; polyetherimides sold by General Electric Company under the ÜLTEM® trademark; poly(vinyl alcohol) sold by Air Products under the VINEX trademark; and polymethylpentene resins sold by Phillips 66 Company under the CRYSTALOR trademark and by Mitsui Petrochemical Industries under the TPX®v trademark. Particularly preferred commercially available ethylene and vinyl alcohol copolymers (such as those sold by EVAL) typically have an average ethylene content of between about 25 mole percent and about 48 mole percent.

A further feature of the microlayered polymer composite of the invention is the increased adhesion force between the layers of elastomeric material and the layers of fluid barrier material. This so-called increased adhesion force is generally achieved by using materials in the individual layers that have functional groups containing hydrogen atoms capable of participating in hydrogen bonding, such as hydrogen atoms of hydroxyl groups or hydrogen atoms attached to nitrogen atoms in polyurethane groups, as well as a number of receptor groups, such as oxygen atoms of hydroxyl groups, oxygens of carbonyl groups in polyurethane and ester groups, and chlorine atoms of PVDC. Microlayered polymer composites characterized by such hydrogen bonding are likely to create an intermediate layer between the elastomer and the fluid barrier materials. The above-mentioned ···>”·

-20- ^r hydrogen bonding is likely to occur, for example, when the elastomeric material is a polyester diol based polyurethane, while the fluid barrier material comprises a polymer selected from copolymers of ethylene and vinyl alcohol, copolymers of polyvinylidene chloride, acrylonitrile and methyl acrylate, polyethylene terephthalate, aliphatic and aromatic polyamides, crystalline polymers and thermoplastic polyurethane engineering plastics. In addition to hydrogen bonding, it is assumed that a certain amount of covalent bonding will also generally occur between the layers of the elastomeric first material and the fluid barrier second material, for example, when polyurethane is present in the adjacent layers, or when one layer comprises polyurethane and the adjacent layer comprises an insulating material such as copolymers of ethylene and vinyl alcohol. The strength of adhesion between adjacent layers of thermoplastic polyurethane and the central layer is likely to be influenced by additional factors, such as orientational forces, induction or Van der Waals forces resulting from the London forces between any two molecules, and dipole-dipole forces between polar molecules.

In addition to the elastomeric polymer and the fluid barrier polymer, the individual layers of the microlayered polymer composite may also contain various conventional additives, such as, but not limited to, hydrolytic stabilizers, plasticizers, antioxidants, UV stabilizers, heat stabilizers, light stabilizers, organic anti-blocking components, colorants (e.g., pigments, dyes, or the like), fungicidal additives, antimicrobial agents (e.g., bactericidal additives, or the like), die release additives, processing aids, and combinations thereof. The hydrolytic stabilizer may be, for example, two commercially available carbodiimide-based hydrolytic stabilizers, STABAXOL P and STABAXOL P-100, products sold by Rhein Chemie of Trenton, New Jersey, USA. Other carbodiimide or polycarbodiimide based hydrolytic stabilizers or stabilizers based on epoxidized soybean oil may also be used with advantage. The total amount of hydrolytic stabilizer used is generally up to 5.0% by weight, based on the total weight of the composition.

-21 —

'.· ·”·*J· ^:, r ·· · · ·· ···· ··

To increase the flexibility and durability of the final product and to facilitate the processing of the material from resin form into membrane or sheet form, plasticizers can also be added to the polymers. Examples include, but are not limited to, plasticizers based on butyl benzyl phthalate (commercially available) (such as Monsanto's Santicizer 160) which have proven particularly useful. Regardless of the type of plasticizer or plasticizer mixture used, the total amount of plasticizer, when used, is usually no more than 20% by weight of the total composition.

The major surfaces of the alternating layers of structural polymer and fluid barrier polymer are substantially parallel to the major surfaces of the composition. A sufficient number of layers of fluid barrier polymer are present in the composite to provide the desired permeation rate of the microlayered composite.

Multilayer polymer composites can be prepared by at least two different methods. According to the first method, the multilayer polymer composite of the invention can be prepared using a two-layer, three-layer or five-layer feeding device, where the feeding device directs the layered polymer stream directly into a static mixer or layer multiplier device. The static mixer device consists of a plurality of, preferably at least five, mixing elements and increases the number of layers geometrically.

According to another possible method, the multilayer polymer composites of the invention can also be produced starting from a first polymer stream consisting of separate layers of polymer material. US-5,094,793 (Schrenk et al.) American patent describes in detail a preferred version of this method. The essence of this is that the first polymer stream consisting of separate layers can be reformed by feeding the molten extrudate exiting the extrusion dies and containing the elastomeric material and the fluid-sealing material separately directly into a two-layer, three-layer or five-layer dispensing device. The first polymer stream is then branched into several streams, which are then led or transferred and individually symmetrically expanded and shrunk, and finally reunited in an overlapping position to form a second polymer stream containing a greater number of individual layers compared to the first polymer stream. The resulting polymer stream also provides a protective

-22- .:1. ·..·.:.. ·-· *·'· may also be coated with boundary layers, as is done in the process disclosed in US-5,269,995 (Romanthan et al.). The protective layers protect the structural and fluid barrier layers from instability and breakage that may occur during layer formation and layer multiplication. The protective layers are provided by a flow of a molten thermoplastic material that is applied to the outer surface of the composite polymer stream along the wall of the coextrusion device to form a protective boundary layer. The protective layer may impart special optical or physical characteristics to the properties of the microlayered polymer composite material, for example, by special coloring, including a metallic color induced by mixing metal or other sheet pigments into the protective boundary layer.

While it is not necessary for all layers to be full layers, i.e., extending in their plane across the entire width of the polymer piece in question, it is desirable for most layers to be substantially full layers extending to the edge of the membrane.

The elastomeric membrane of the invention comprises the microlayered polymer composite, either as a separate layer or as one of the layers of a laminate. The membrane may be of any suitable length and width to form the desired hose or pressure vessel for use in footwear. The average thickness of the microlayered polymer composite of the membrane may vary over a wide range, for example, from 75 μm to 0.5 cm. The average thickness of the microlayered polymer composite is preferably at least about 50 μm, more preferably at least about 75 μm to about 0.5 cm, even more preferably from about 125 μm to about 0.5 cm, and most preferably from about 125 μm to about 0.15 cm. When the microlayered polymer composite is used to make a hose for use in footwear, the average thickness is preferably from about 75 μm to 0.1 cm, while membranes for use in hydropneumatic reservoirs are generally thicker. In a preferred embodiment of the membrane according to the invention, the average thickness of the microlayered polymer composite is at least 125 µm.

One possible embodiment of the membrane according to the invention is formed as a laminate comprising the microlayered polymer material in the form of one or more laminated layers. The alternating layers are preferably those listed above,

-23 « · · · · ·*· ·· is selected from polymers that can be used as a structural material of a microlayered material. The alternating layers are more preferably polyurethane materials. The laminate may consist of any number of alternating layers, the number of layers is preferably from 1 to about 5, and more preferably from 1 to 3. The further layers of the laminate are preferably selected from the thermoplastic elastomer materials previously mentioned and suitable as structural layers of the microlayered polymer composite. A preferred embodiment of the membrane according to the invention is formed as a laminate of at least one type A layer comprising an elastomeric polyurethane and at least one type B layer comprising a microlayered polymer composite. In further preferred embodiments, the laminate comprises an A-B-A or A-B-A-B-A layer arrangement.

When the microlaminated polymer film is used to form a laminate, the average thickness of the laminate is between about 75 μm and about 0.5 cm, preferably between about 75 μm and about 0.13 cm. The thickness of the microlaminated polymer film of the laminate preferably varies between about 6.35 μm and about 2600 μm.

The hose of the invention can be formed by RF (radio frequency) welding of two sheets of microlaminate material or laminate containing microlaminate, especially in the case where one of the layers is a polar material, such as polyurethane. Non-polar materials, such as polyolefins, can be joined by ultrasonic or thermal welding. In addition to these methods, other well-known welding techniques can also be used.

When the hose is used as a cushioning structural element in footwear, such as shoes, the hose can be inflated to an internal pressure of at least about 20.68 kPa and up to about 344.74 kPa, preferably with nitrogen. The hose is preferably inflated to a pressure of between about 34.474 kPa and about 241.32 kPa, more preferably between about 34.474 kPa and about 206.84 kPa, more preferably between about 68.5 kPa and about 206.84 kPa, and even more preferably between 103.42 kPa and 172.37 kPa. It will be apparent to those skilled in the art that the required and preferred pressure ranges for operation in applications other than footwear may vary considerably, and are determined by the art.

-24- Η· can be determined by qualified specialists. The pressures in the collection tanks can, for example, range up to 6.89 MPa.

The membranes of the invention are advantageously useful in the formation of cushioning structural elements of footwear. In such applications, the membranes are advantageously capable of retaining the entrapped gas for a relatively long period of time. In a particularly advantageous embodiment, the membrane can lose up to 20% of the initially inflated gas pressure in about two years. In other words, products initially inflated to an equilibrium pressure of between 137.9 kPa and 151.7 kPa should retain a pressure of at least between 110.3 kPa and 124.1 kPa for at least two years.

The gas permeability of the material to the gas used for inflation, which is preferably nitrogen, is at most 10 cm ³ /m ² .atm.day, preferably at most 3 cm ³ /m ² .atm.day, and more preferably at most 2 cm 3 /m 2 .atm.day.

Microlaminated polymer composites are more resistant to delamination and fracture. By dividing the fluid barrier layer into multiple layers, the fracture resistance of the individual layers is increased. Without going into any theoretical analysis, it is believed that, assuming the same external dimensions and constant crack density, a laminate made up of thinner layers is likely to contain fewer cracks in the individual layers, so that a microlaminated polymer composite containing the same amount of fluid barrier material as a conventional laminate but distributed over multiple layers will contain significantly more fluid barrier material in non-fractured layers than a laminate in which each crack forms a fracture under load. Furthermore, if a fracture occurs in the fluid barrier layer in a microlaminated polymer composite, dissipation processes along the interfaces will help to confine the fracture to a single layer. The fluid permeation rate is not significantly affected if breaks develop in some fluid-isolating layers, as the adjacent fluid-isolating layers still force diffusing substances to take a detour to pass through the membrane.

·· ·* φ *· J

-25- .:λ

Among others, the following methods are known: extrusion, blow molding, injection molding, vacuum forming, injection molding, pressure forming, hot-melt bonding, casting, melt casting, RF welding.

1-3 illustrate an athletic shoe 10 including a sole structure and a cushioning structural member made from the membrane of the present invention. The shoe 10 has an upper 12 to which a sole 14 is attached. The upper 12 may be made from a variety of conventional materials, including, but not limited to, leathers, vinyls, and nylons, and other generally woven fibrous materials. The upper 12 typically includes reinforcements around the toe 16, the lace loops 18, the upper 20, and the heel 22, as illustrated in FIG. 1. As is common with most athletic shoes, the sole 14 extends the entire length of the shoe 10 through an arch 24 from the toe 16 to the heel 20.

The illustrated sole 14 includes one or more cushioning structural elements or tubes of the invention, generally located in the midsole 14. As shown, for example, in FIGS. 1-3, the membranes 28 of the invention may be formed in the form of elements of different geometries, such as a plurality of separate tubular elements spaced apart and parallel to each other in the corner portion 22 of the midsole 26 of the sole 14. The tubular elements are hermetically sealed to retain the gas introduced therein. The insulating properties of the membrane 28 may be provided by a single layer 30A of a microlaminated polymer composite, as shown in FIG. 24, or by a layer 30 of a microlaminated polymer composite disposed on the inner surface of an outer layer 32 of a thermoplastic elastomer, as illustrated in FIGS. 4 and 5. As shown in FIGS. 8-18, As shown in Figures 1-3, the membranes 28 of the invention, whether single or multi-layer, can be formed into products of a variety of shapes or configurations. It is noted that the membranes 28 formed into cushioning structural elements for use in footwear can be fully or partially incorporated into the outsole 14 or midsole 26 of the footwear. In one such embodiment, the tube is formed as part of the sole 14 and forms at least a portion of the outer surface of the shoe 10 at the sole 14.

Referring back to Figures 1-3, the membrane 28 of the present invention is illustrated as a cushioning structural element for use as a component of footwear. The membrane 28, in the embodiment shown in Figure 24, is comprised of a single layer 30A of a microlaminated polymer composite of elastomeric material, preferably one or more polyester-diol based polyurethanes, and one or more fluid barrier polymers.

Figures 6 and 7 illustrate a possible further embodiment of the membrane 28A of the invention in the form of a multilayered, elongated tubular component. The modified membrane 28A is essentially the same as the membrane 28 shown in Figures 4 and 5, except that a continuous third layer 34 is disposed along the inner surface of the layer 30, so that the layer 30 is sandwiched between the outer layer 32 and the innermost layer 34. The innermost layer 34 is also preferably formed of a thermoplastic polyurethane material. In addition to the benefits of the increased resistance of the layer 30 to abrasion, the layer 34 is also likely to contribute to the creation of high-quality welds, which allows the formation of three-dimensional (i.e., 3-dimensional) shapes, such as cushioning structures, such as footwear.

The membranes 28, 28A, similar to those shown in Figures 1-7 and Figure 24, are preferably formed from extruded tubes. The tubes are extruded longitudinally, continuously, and typically wound in 15 m lengths to form inflatable hoses for use in footwear. The individual tubes are formed to the desired length by RF welding or heat bonding. The RF welded or heat bonded, hermetically sealed inflatable hoses are then separated from each other by cutting at the welded areas between adjacent hoses and inflating the hose to a desired initial pressure between 20.68 kPa ambient pressure and 689.5 kPa, preferably between 20.68 kPa and 344.738 kPa, where nitrogen gas is preferably used for inflation. We would also like to note here that the hoses can also be formed from so-called sheet-extruded tubes known to those skilled in the art by welding an internal geometry into the tube in question.

Figures 8-10 illustrate possible further embodiments of the membranes 28B, 28C, 28D according to the invention. Sheets or films formed from extruded single-layer films or coextruded two- or three-layer films are formed to the desired thickness. The thickness of the coextruded sheets or films is, for example, preferably 12.5 mm for the 30 layers.

- 27 - χ. <.'* - -t ^r μιτι to 250 pm, while for the outer layer 32 and the layer 34 it is between 112.5 μηι and 2500 μm. In the case of a single-layer cushioning structural element, the average thickness is usually between 125 μm and about 1500 μm, and more preferably between about 375 μm and about 1000 μm.

Figures 12-16 show blow molded inflatable membranes 28D, 28E. The tubes are formed by extruding a layer of a melt of a microlayered polymer composite, or coextruding melts of two or three layer films, one of which is a microlayered polymer composite, as shown in Figures 21-23. The melts are then blown and shaped using conventional blow molding techniques. The resulting tubes, such as those shown in Figures 12 and 15, are inflated to the desired initial pressure with the desired filling gas, and then sealed, for example, by RF welding, at the inflation opening 38 indicated in Figure 12.

Figures 17 and 18 show a possible further embodiment of the membrane 28F of the invention. The air tube is formed by forming an extruded single layer or coextruded multilayer tube having a thickness within the desired thickness range. The tube is formed into a flat, flat shape and the opposing walls are welded together at selected points and at the ends using conventional heat bonding or RF welding techniques. The cushioning structural element is then inflated through the formed inflation opening 38 using nitrogen as the filling gas to the desired pressure, which ranges from 34.47 kPa ambient pressure to 689.5 kPa pressure, preferably from 34.47 kPa pressure to 344.7 kPa pressure.

In addition to the use of the membranes 28A-F according to the invention as cushioning structural elements or air hoses described above, a further very advantageous area of use is in the collection tanks shown in Figures 19, 20 and 25.

Figure 25 shows a reservoir formed from the single-layer membrane 124 described above. Similarly, Figures 19 and 20 show two possible exemplary embodiments of a reservoir formed from the multilayer membrane 124 of the present invention. Reservoirs, or more specifically pressure reservoirs, are used in vehicle injection systems, brake systems, industrial pressure reservoirs, or other applications where two potentially different fluids are at different pressures. The membrane 124 divides the pressure reservoir into two chambers or compartments.

-28, where one contains a gas, such as nitrogen, and the other a liquid. The membrane 124 has an annular rim 126 and a flexible body 128. The annular rim 126 is attached to the inner surface of the spherical collection container along its circumference so that the body 128 divides the collection container into two separate chambers. The flexible body 128 generally moves diametrically within the spherical collection container, its instantaneous position depending on the gas pressure on one side and the liquid pressure on the opposite side.

The product shown in Figure 20 illustrates a pressure vessel embodiment having a first layer 114 of the microlayered polymer composite of the present invention. The product also includes layers 112 and 116 of one or more thermoplastic elastomers. As can be seen, the first layer 114 extends along only a portion of the body of the collection vessel 128. Such embodiments, referred to as intermediate structures, may be desirable in situations where the likelihood of separation of the layers in certain parts of the product is extremely high. Such a portion may be considered to be the region extending along the annular edge 126 of a hose or partition manufactured for pressure vessels having a layered embodiment. Because membranes formed from the laminate of the invention are more resistant to delamination, and because they are more resistant to gas leakage along the interfaces of individual layers 112, 114, 116 - such as occurs along the edge 126 as a result of capillary action - it is possible that the membrane 124 may have regions from which layer 114 is absent.

The membranes of the invention can be produced by a variety of manufacturing processes, including, but not limited to, extrusion, profile extrusion, injection molding, and blow molding, and then formed into inflatable tubes by hot-sealing or RF welding of tubes and sheet-extruded films. In order to achieve optimal wetting for maximum adhesion between the contacting portions of the layers 30, 32, 34, and to enhance the strength of the hydrogen bonds between the layers when using materials susceptible to this, the materials are preferably combined at a temperature of between about 150°C and about 240°C and at a pressure of at least about 1.38 MPa. The membranes of the multilayer laminate are produced by coextruding the microlaminated polymer composite forming layer 30 and the elastomeric material forming layer 32. The multilayer laminate films are formed by

-29- The films in question are subjected to heat bonding or RF welding to form flexible inflatable hoses.

Similarly, the membranes 124 used as the basis for the products shown in Figures 19, 20 and 25 can also be produced as coextrudates, thus providing a good example of the desired hydrogen bonding between the layers 114, 112 and 116. For the production of products such as the pressure vessel bulkhead by a multilayer process, for example by blowing, any of the commercially available blow molding machines can be used, such as the Bekum BM502 using a BKB95-3B1 coextrusion head (not shown) or the Krup KEB-5 using a VW60/35 coextrusion head (also not shown).

Whether the membranes of the invention are formed as sheets, substantially closed containers, cushioning structures, collection tanks, or other structures, they preferably have a tensile strength of at least about 17.24 MPa, a tensile modulus at 100% elongation of between about 2.41 MPa and 20.68 MPa, and/or can be stretched to an extent of at least about 250% to about 700%.

Sheets can be produced by forcing molten polymer produced in a die through a suspended sheet former. The hollow tubes and melts used in blow molding are formed by forcing molten plastic produced in a die through a ring former.

The microlayered polymer composite may also be used as one layer of a multilayer laminate. A multilayer process known as sheet coextrusion is also advantageously used to prepare the membranes of the invention. Sheet coextrusion generally involves the simultaneous extrusion of two or more plastics through a single die, where the individual materials are bonded together in discrete, closely adhering layers that form a single extruded product.

The equipment required for producing the coextruded sheet comprises a die for each type of resin connected to a coextrusion feeder as illustrated in Figures 21 and 23, which dies are available from a number of commercial sources, including, for example, Cloeren Company of Orange.

-30 (Texas, USA) and are available from Production Components Inc. (Eau Claire, Wisconsin, USA).

The coextrusion feeder 150 of the apparatus illustrated in Figure 21 is composed of three sections: a first section 152, a timing section 154, and a transfer section 156. The first section 152 forms the inlet port that connects the individual dies and introduces the individual circular resin streams into the timing section 154. The timing section 154 shapes each incoming resin stream into a rectangular cross-section, the dimensions of which are proportional to the final desired thickness of each layer. The transfer section 156 combines the individual rectangular cross-section layers that are separate from each other into a single square-shaped port. The melting point of each TPU layer should generally be between about 150°C and about 240°C. To achieve optimum adhesion between successive layers, the actual temperature of each molten polymer stream should be adjusted so that the viscosity coefficients of the molten polymer streams are approximately the same. The combined laminated molten polymer stream is then formed into a single rectangular molten extrudate in a sheet former 158, preferably a suspended rack-shaped one, commonly used in the plastics processing industry, as shown in Figure 22. The extrudate is then cooled while being formed into a rigid sheet by casting or rolling using rollers 160.

Similar to sheet extrusion, the equipment for producing coextruded tubes includes a separate die for each different resin type, with each die connected to a common multi-hole tube former. The molten materials exiting each die enter the multi-hole forming unit shown in Figure 23, which is commercially available from a number of sources, including Canterberry Engineering Inc. (Atlanta, Georgia, USA) and Genca Corporation (Clearwater, Florida, USA), and then proceed through separate circular flow channels 172A, 172B for each molten material. The flow channels 172A, 172B then form a circular opening, the size of which is proportional to the desired thickness of each layer. The individual melts are then combined into a single molten polymer stream just prior to the former inlet 174. The combined stream

-31 then flows through a channel 176 formed by the circular opening between the outer surface 178 of the cylindrical mandrel 180 and the inner surface 182 of the cylindrical forming housing 184. The tubular extrudate then exits the forming housing 184 and can be cooled to a tubular shape by a variety of conventional tube sizing methods. Although a two-layer tube is shown in FIG. 23, it will be apparent to those skilled in the art that additional layers can be added to the two-layer tube through separate flow channels.

Regardless of the plastic molding process used, in order to achieve adhesion between the individual layers of the laminated product over the intended length or piece, it is desirable to use a thick, flowing melt of the materials. It is noted again that the multilayer processes used should be carried out at temperatures maintained between about 150°C and about 240°C. It is also important to maintain a pressure of at least 1.38 MPa at the point where the separate layers are joined, i.e. where the hydrogen bonding described above is formed.

As previously discussed, in the possible embodiments of the laminated membrane according to the invention - especially with regard to membranes used as cushioning structural elements in footwear - in addition to excellent adhesion, it is also our goal to develop membranes that are capable of retaining the entrapped gases for an extended period of time. In general, membranes with a gas permeation rate of up to 15.0 cm ³ /m ² .atm.day for nitrogen serve as acceptable starting materials for long-life applications. The gas permeation rate in question is measured according to the method set forth in ASTM D-1434-82. Therefore, while the membranes according to the invention may vary in thickness, depending mainly on the intended use of the end product, their gas permeation rates are preferably up to 15.0 cmW.atm.day, regardless of the thickness of the membranes. Similarly, although nitrogen gas is preferred as the filling gas in many embodiments, which is the basis for determining gas permeation rates according to ASTM D-1434-82, the membranes of the invention may be filled with a variety of gases and/or liquids.

In preferred embodiments of the membranes according to the invention, the gas permeation rate for nitrogen is 10.0 cm ³ /m ² .atm.day, or more preferably no more than 7.0

-32cm ³ /m ² .atm.day, more preferably at most 5.0 cm ³ /m ² .atm.day, even more preferably at most 2.5 cm ³ /m ² .atm.day. In a particularly preferred embodiment of the membranes according to the invention, the membranes have a gas transmission rate for nitrogen of 2.0 cm ³ /m ² .atm.day.

In addition to the increased resistance to gas permeation shown by many products obtained from polyester diol-based polyurethanes described above, the durability of products made from polyester diol-based polyurethanes also shows a significant increase in durability compared to products made from thermoplastic polyurethanes not containing polyester polyols.

After the cushioning structural elements constituting the specimens were inflated with nitrogen gas to a pressure of approximately 137.9 kPa, each cushioning structural element was subjected to cyclic compression by a reciprocating piston equipped with a pressure plate of approximately 10 cm in diameter. The stroke length of each piston was adjusted so that the pistons compressed the specimens to an average of 25% of their initial inflation thickness at maximum stroke length. The reciprocating pistons were then operated cyclically until partial failure of the specimens was detected. Partial failure of a given specimen was defined in this case as reaching a state in which, as a result of the leakage of a specified amount of nitrogen gas and the resulting deflation of the specimen, the arms arranged at the same location on the cushioning structural elements came into contact with a microswitch, interrupting the movement of the pistons associated with the specimens. When this occurs, the total number of cycles or impacts the sample undergoes to partial failure is recorded for each sample; a higher number of impacts indicates a more durable material. For a permanently inflated cushioning component to be suitable for use as a part of footwear, it should preferably withstand at least 200,000 cycles. It is often desirable to produce products that are relatively transparent in addition to being highly durable, i.e., meet certain standards in terms of their measured level of yellowness and the amount of light that passes through the material. The light transmission of the product may be an important consideration, for example, in the case of cushioning components used as part of footwear that remain visible after installation. Cushioning components made from materials such as Pellethane 2355-85 ATP or Pellethane 2355-87 AE are suitable for use as a part of footwear.

-33 proved to be extremely advantageous for use, as their measured yellowness and the amount of light transmitted by them were acceptable from the point of view of practical applicability.

Although the hoses according to the invention have been described as particularly useful embodiments for cushioning structural elements for footwear and also for collection containers, it is evident that the membranes according to the invention have a wide range of applications, including but not limited to, for example, in the form of hoses for use in inflatable objects, such as American footballs, basketballs, soccer balls, inner tubes; in flexible flotation devices, such as tubes or lifeboats; as components of medical aids, such as catheter balloons; in pieces of furniture, such as parts of chairs and seats; as parts of bicycles or saddles; as parts of protective devices, such as shin guards and helmets; as support elements for pieces of furniture, and more preferably as lumbar supports; as components of prosthetic or orthopedic devices; as parts of tires, preferably as the outer layer of the tire; and finally as components of certain leisure equipment, such as inline or roller skate wheels.

In the following, we intend to describe the properties of the membranes according to the invention in more detail through two examples.

The following process is used to produce a microlayer laminate. Two die sets, one for the polyurethane elastomer and one for the ethylene-vinyl alcohol copolymer (EVOH), are connected to a feeder. The molten polymer is fed from the die sets into the feeder where a three-layer polyurethane/EVOH/polyurethane composition stream or a five-layer polyurethane/EVOH/polyurethane/EVOH/polyurethane composition stream is formed. From the feeder, the polymer stream is then continuously fed into a static mixer where a stream of polyurethane and EVOH microlayers is formed. The microlayer stream is then fed into a sheet former and from there into a three-roller draw assembly. The laminate is cooled, then slit and welded along a straight line.

.EXAMPLE

In the above process, the polyurethane used was Pellethane 2355 85ATP (polyester polyurethane copolymer) with a hardness of 85 shore-A, sold by Dow Chemical Co.,

-34while LCF 101A (an ethylene-vinyl alcohol copolymer containing 32% of EVOH) sold by Eval is fed into a five-stream feeder. The process leaving the feeder is fed into a seven-element static mixer. The resulting microlayered polymer composite contains 15% by weight of LCF 101A and has a thickness of approximately 500 pm. Figure 26 shows a cross-section of the microlayered polymer composite obtained by the above process, which was taken with an optical microscope in reflection mode. The EVOH layers were stained with iodine solution. The photograph shown in Figure 26 shows at least 28 layers of material.

The microlayered polymer composite is:

- tensile strength

- elongation at break

- tensile modulus

- tensile modulus at 50% elongation

- tensile modulus at 100% elongation

- tensile modulus at 200% elongation - tensile modulus at 300% elongation measured values of the physical properties of

44.77 MPa;

490%

304.75 MPa;

12.82 MPa;

13.90 MPa;

17.83 MPa;

25.79 MPa.

EXAMPLE

A microlayered polymer composite was prepared according to Example 1, except that the final material contained 7.5 wt% LCF 101A. The measured values of the physical properties of the microlayered polymer composite are as follows:

-tensile strength 52.19 MPa;

- elongation at break 545 %

- tensile modulus 194.26 MPa;

- tensile modulus at 50% elongation 10.77 MPa;

- tensile modulus at 100% elongation 12.25 MPa;

- tensile modulus at 200% elongation 16.68 MPa;

— tensile modulus at 300% elongation 25.01 MPa,

- gas transmission rate (for nitrogen) 0.

Claims (41)

-35PATENT CLAIMS 1. An elastomeric insulating membrane, characterized in that it comprises a microlayered polymer composite having an average thickness of at least about 50 pm, wherein the microlayered polymer composite comprises at least about ten microlayers each having a thickness of up to about 100 pm, the microlayers being formed alternately of at least one fluid-insulating material and at least one elastomeric material. 2. A membrane according to claim 1, characterized in that it forms a pressurized tube containing an inflation gas. 3. The membrane according to claim 2, characterized in that its nitrogen permeation rate against the blowing gas is at most 10 cm/m.atm.day. 4. The membrane of claim 1, wherein the elastomeric material is selected from polyurethane elastomers, flexible polyolefins, styrene-based thermoplastic elastomers, polyamide elastomers, polyamide-ether elastomers, ester-ether elastomers, ester-ester elastomers, flexible ionomers, thermoplastic vulcanizates, flexible polyvinyl chloride homopolymers and copolymers, flexible acrylic polymers, and combinations thereof. 5. The membrane of claim 1, wherein the elastomeric material comprises a polyurethane elastomer. 6. The membrane of claim 1, wherein the elastomeric material is selected from thermoplastic polyester diol-based polyurethanes, thermoplastic polyether diol-based polyurethanes, thermoplastic polycaprolactone diol-based polyurethanes, thermoplastic polytetrahydrofuran diol-based polyurethanes, thermoplastic polycarbonate diol-based polyurethanes, and combinations thereof. 7. The membrane according to claim 6, characterized in that the elastomeric material comprises a thermoplastic polyester diol-based polyurethane. 8. The membrane of claim 7, wherein the polyester diol of said polyurethane is formed by the reaction product of at least one dicarboxylic acid and at least one diol. 9. The membrane of claim 8, wherein the dicarboxylic acid is selected from adipic acid, glutaric acid, succinic acid, malonic acid, oxalic acid, and mixtures thereof. 10. The membrane of claim 8, wherein the diol is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, and mixtures thereof. 11. The membrane according to claim 8, characterized in that the dicarboxylic acid comprises adipic acid and the diol comprises 1,4-butanediol. 12. The membrane of claim 7, characterized in that the polyurethane is polymerized using at least one chain extender selected from diols and diamines. 13. The membrane of claim 12, wherein the chain extender is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and mixtures thereof. 14. The membrane of claim 12, wherein the ratio of polyester diol equivalents to chain extender equivalents is between about 1:1 and about 1:8. 15. The membrane of claim 1, wherein the fluid barrier material is selected from ethylene-vinyl alcohol copolymers, polyvinylidene chloride, acrylonitrile copolymers, polyethylene terephthalate, polyamides, crystalline polymers, polyurethane engineering plastics, and combinations thereof. 16. The membrane of claim 1, wherein the fluid barrier material comprises an ethylene-vinyl alcohol copolymer. 17. The membrane of claim 16, wherein the ethylene-vinyl alcohol copolymer has an ethylene copolymer content of between about 25 mole % and about 50 mole %. 18. The membrane of claim 16, wherein the ethylene-vinyl alcohol copolymer has an ethylene copolymer content of between about 25 mole % and about 40 mole %. 19. The membrane of claim 1, wherein the microlayered polymer composite has at least about fifty microlayers. 20. The membrane of claim 1, wherein the microlayered polymer composite has a number of microlayers ranging from about thirty to about one thousand. 21. The membrane of claim 1, wherein the microlayered polymer composite has a number of microlayers between about fifty and about five hundred. 22. The membrane of claim 1, wherein the average thickness of the microlayers of fluid barrier material, independently of each other, is no more than about 2.5 µm. 23. The membrane of claim 1, wherein the microlayers of fluid barrier material have an average thickness independently of each other of between about 0.01 pm and about 2.5 pm. 24. The membrane of claim 1, wherein the microlayered polymer composite has an average thickness of between about 125 microns and about 0.5 cm. 25. The membrane of claim 1, wherein the microlayered polymer composite has an average thickness of between about 125 microns and about 0.1 cm. 26. The membrane of claim 1, characterized in that it is a laminate of at least one type A layer comprising an elastomeric polyurethane and at least one type B layer comprising a microlaminated polymer composite. 27. The membrane of claim 26, wherein the laminate comprises an AB-A ply arrangement. 28. The membrane of claim 26, wherein the laminate comprises an AB-A-B-A layer arrangement. 29. The membrane of claim 1, wherein the microlayered polymer composite is formed with an outer protective layer. 30. The membrane of claim 26, wherein the average thickness of the laminate is no more than about 0.5 cm. 31. The membrane of claim 26, wherein the B-type layer has an average thickness of between about 6.35 µm and about 2600 µm. 32. The membrane of claim 2, characterized in that it has a nitrogen permeability 3 2 The speed of attack is up to 10 cm /m .atm.day. 33. The membrane of claim 2, characterized in that it has a nitrogen permeability 3 2 has a maximum speed of 3 cm /m .atm.day. 34. The membrane according to claim 2, characterized in that its nitrogen permeation rate is at most 2 cm/m.atm.day. 35. A cushioning structural element, characterized in that it comprises a membrane according to any one of claims 1-34. 36. The membrane of claim 2, wherein the inflation gas pressure is at least 20.68 kPa. 37. The membrane of claim 2, wherein the inflation gas pressure is between 20.68 kPa and 344.74 kPa. 38. The membrane of claim 2, wherein the inflation gas is nitrogen. 39. Footwear, characterized in that it comprises at least one pressurized hose according to claim 36. 40. Footwear according to claim 39, characterized in that the hose is formed as part of the sole (14) of the footwear. 41. Footwear according to claim 39, characterized in that at least a portion of its outer surface is formed by the hose. Instead of the notifier, the following is authorized: DANII Patent and Trademark Office Ltd. Our file number: 94171-8452/SZT/SZT Our administrator: Zsolt Szabó /1 P 0003729 LIST OF NOMINATIONS 10 shoes 12 shoe upper 14 soles 16 nose part 18 ring 20 top 22 corner part 24 foot arch part 26 midsole 28 membrane 28A membrane 28B membrane 28C membrane 28D membrane 28E membrane 28F membrane 30 layers 30A layer 32 layers 34 layers 38 inflator 112 layers 114 layers 116 layers 124 membrane 126 edge 128 body 150 coextrusion feeder 152 first section 154 scheduling section 156 passage section 158 plateformer 160 cylinder 172A flow channel 172B flow channel 174 entrance 176 channels 178 external surface 180 pin 182 internal surface 184 formation house 94171-8452/SZT/SZT